The long-term objective of this research is the development of compact, robust, and userfriendly femtosecond-pulse laser sources for applications in biology and medicine. Examples include multi-photon microscopy, optical coherence tomography imaging, and femtosecond comeal surgery. In the last few years alone, researchers in biology and medicine have demonstrated numerous new applications of femtosecond-pulse lasers. Advanced laser sources must be developed if these are to find acceptance outside specialized research laboratories. Such sources will provide researchers in the biological and biophysical sciences much greater access to new techniques while enhancing and expanding their capabilities. The primary aim is to develop high-energy fiber lasers. As a result of recent advances, the development of short-pulse sources with capabilities that will exceed those of bulk solid-state lasers is realistic. Fibers and semiconductors offer the possibility of completely integrated devices, which will be required for new short-pulse techniques to attain widespread use. A secondary focus of this work will be the development and application of measurement capabilities in support of biological imaging techniques. This will include the assessment of semiconductor nanocrystals as fluorophores in multi-photon microscopy. The development of new and/or enhanced capabilities for visualizing and affecting tissue at levels ranging from molecular to macroscopic has had obvious health benefits and similar or greater impact can be expected in the future.